The present invention relates to optical bar code scanning systems and more particularly to a portable bar code scanning device in which a bar code label is moved across a transparent surface on which is projected a scanning pattern for scanning the bar code label during a merchandise checkout operation.
In present-day merchandising point-of-sale operations, data pertaining to the purchase of a merchandise item is obtained by reading data encoded indicia such as a bar code label printed on or attached to the merchandise item. In order to standardize the bar codes used in various point-of-sales checkout systems, the grocery industry has adopted a uniform product code (UPC) which is in the form of a bar code. Reading systems which have been constructed to read this type of bar code include hand-held optical scanners which are moved across the bar code and stationary optical scanners normally located within the cabinet structure of a checkout counter in which the bar code is read when a purchased merchandise item is moved across a window constituting the scanning area of the counter, which movement is part of the process of loading the item into a baggage cart. Hand-held scanners emit a single scan line which is directed over the bar code by the operator while the stationary optical scanners emit a multiline scan pattern through which the bar code label is moved, enabling a higher throughput of scanning bar code labels to occur over that of hand-held scanners. Where the merchandise consists of soft materials such as clothing or other types of soft materials, hand-held scanners have been employed to read the bar code labels attached to the material in which the bar code label is manually positioned adjacent the hand-held scanner. It has been found that this type of scanning operation has been ineffective in many cases because the bar code label was not positioned within the depth of field of the scanner or that the projected scan pattern was not properly positioned on the bar code label. Because of this, there has arisen a need for a portable scanning device which can be moved to a plurality of positions within the business establishment allowing a hands free scanning operation to occur. An example of this type of scanning device may be found in the above cited NCR patent application Ser. No. 625,331. One drawback of this type of scanning device is that the scanning aperture is oriented in only one direction which, in some installations, was found to limit the scanning operation due to limited counter-space at the checkout station.
The background art known to the applicants at the time of the filing of this application includes U.S. Pat. No. 4,369,361 which discloses a portable stand-alone desk-top laser scanning workstation including a laser scanning head mounted above a support base facing the operator in which objects bearing bar code symbols to be scanned are passed under the scanning head, and U.S. Pat. No. 4,766,297 which discloses a support member for supporting a portable hand-held scanning device in which the support member includes structure for sensing the presence of an object between the scanning head portion and the base portion of the support member and for automatically initiating a reading of a bar code symbol by the portable hand-held scanning device each time the sensing structure senses the presence of an object.